This invention is concerned with organosiloxane foams.
It has been proposed to employ two-part curable organosiloxane foam forming compositions for a variety of uses.
For example it has been proposed to use two-part, room temperature curable compositions to provide dressings for open granulating wounds. For example, G.B. Patent Specification No. 1 492 581 describes a process in which the two parts of the composition are mixed and then poured into an open wound where the composition foams and cures to provide an elastomeric foam dressing. Such compositions may comprise for example poly(dimethylsiloxane) and finely divided filler base or "part A", and a catalyst part or "part B" comprising catalyst material for promoting room temperature curing of the composition according to the scheme .tbd.SiOH+HSi.tbd..fwdarw..tbd.Si--O--Si.tbd.+H.sub.2. In this way, one may provide comfortable, non-adherent dressings conforming to the contours of the wound which are inter alia flexible, resilient, permeable to air and somewhat absorbent.
Such a procedure for producing dressings leads to a variety of advantages related to improved patient comfort e.g. resulting from the resilient non-adherent characteristics of the dressing and reduced care from specialist nursing staff e.g. due to the increased possibility for the patient to remove the dressing to permit washing and/or disinfecting of the wound and dressing, followed by replacement of the dressing.
While it is possible to take advantage of this proposal, the tendency of the filler to separate from the other components during storage resulting in the formation of a thick deposit in the part A during storage of the compositions employed has necessitated not only proper mixing together of the parts A and B but also thorough mixing of the part A prior to admixture with the part B. Thus, the step of mixing the part A of the composition just prior to use is a critical step in order to ensure that a suitably foamed, cured, uniformly resilient product is produced and in order to exploit the considerable advantages available by use of the process. When this step is not carried out adequately or at all (as may happen in practice) mediocre quality dressings result.
It is difficult to rectify improper mixing of curable compositions because very often the fact of improper mixing is not recognized until after the supposedly curing composition has been applied to its allotted position. After recognition of failure to provide a suitably cured mass it becomes desirable to remove the defective material, clean up the site and to achieve the desired result by correct application or by some other practice. Such remedial operations are troublesome and inconvenient and are especially so in those cases where the product is used to provide a treatment for an open wound for example on the human body.